Field
Various communication systems may benefit from network assisted automatic clustering. For example, wireless communication systems may benefit from such clustering that enables victim to victim communication after the network becomes unavailable, for example due to a disaster.
Description of the Related Art
Cellular network and Wi-Fi network coverage is pervasive, particularly in urban areas. Depending upon available capacity at a given location over a time, the network can deliver requested service to users. In addition, in connection with the third generation partnership project (3GPP), for example, device-to-device (D2D) and Proximity Service (ProSe) are being created.
A goal of D2D is to enable direct communication between the devices. This direct communication can increase capacity of wireless base station. D2D, therefore, allows combining infrastructure-mode and ad hoc communication. Much study of ProSe and D2D is related to network assisted services. There are, however, scenarios in which coordinated D2D ad hoc communication may be needed. One such situation is a disaster scenario. For example, when a disaster happens a network can get disturbed and existing schemes do not allow victims, namely users who are trapped inside the disaster region, to communicate to another victim in coordinated fashion. Such coordinated communication between victims can be referred to as victim-to-victim (V2V) communication.
Disasters are exceptional events that can be either man made, such as terrorist attacks, or natural, such as earthquakes, wildfires and floods. Disasters can create emergency situations and cause physical and social disorder. In these emergency situations, food, water, shelter, protection and medical help may be needed, and the effort needed to provide these basic services to the victims may need to be coordinated quickly.
In disasters, typically most of the casualties occur within 48 hours of disaster incident. Moreover, cellular network (towers) and communication and power lines that were present before disaster are often not operational. Victims, including users affected in the disaster area, conventionally cannot get in touch with their families.
Thus, victims in the disaster region typically help each other until proper communication and rescue operations are in place. Moreover, disaster relief operations can take place with the help of medical departments, fire departments, and police departments, but these public safety organizations typically establish communication very late. Immediately after a disaster, victims typically try to help each other, as first hand help. Moreover, victims typically attempt to comfort themselves by searching for their friends and families in a nearby disaster region. Movement of victims may typically be restricted to less than two kilometers.
Conventionally, when people in a disaster situation look for cellular coverage or any other established services, they are not available. Moreover, victims may want to help each other and may move in groups. Nevertheless, conventionally radio systems are unable to extend D2D to V2V services in the event of total network collapse or failures.
Rather, existing D2D schemes focus mostly on user communication by means of direct D2D, and public safety when the network is not available. In a public safety case, a first public safety user equipment (PUE1) can directly communicate with another public safety user equipment (PUE2) or with the public safety control center. The goal of this approach is to have network assisted D2D communication or with proximity based user equipment (UE) to UE communication via application support. Conventionally, victim to victim communication is missing, even though victims may need to help themselves immediately after disaster.
FIG. 1A illustrates a communication system prior to a disaster event. Thus, FIG. 1A shows a snapshot of a network and communication between endpoints. Various UE distributed in a given area can be communicating either directly or through the internet. All possible combinations can be examined by considering roaming, WLAN/Cellular/D2D and network assisted communication.
As shown in FIG. 1A, UE1-4 are in close proximity and are engaged in group communication amongst themselves, while being served by Cell1. UE-5 is idle and may be in close proximity with either UE1-4 or UE-6. UE-6 is engaged in internet browser activity and has a connection, as a communicating path, established to internet via cell-1.
As shown in FIG. 1A, UE7-10 are engaged in device to device communication. UE7 and UE8 can also be served by cell1 and UE9 and UE10 can also be served by cell2, although UE8 can be in D2D communication with UE10 and UE7 can in D2D communication with UE9. Moreover, cell1 and cell2 may be run by different operators.
UE11 is, in FIG. 1A, having D2D with UE12; it is possible that UE11 is in HomePLMN and UE12 is roaming. UE13 and UE14 are engaged in D2D conversation and may be using WLAN direct communication. UE15, as shown, does not having any proximity service enabled as part of UE15's profile, but may be near UE13 or UE14. Another possible scenario is that UE14 may be communicating to UE6 over the internet.
FIG. 1B illustrates a communication system subsequent to or during a disaster event. Thus, FIG. 1B shows a snapshot of the network after the beginning of a disaster. As shown in FIG. 1B, communicating cell towers cell1 and cell2 are not available any more, thus the communicating UEs that use network assisted D2D may not work. If there are UEs that are communicating directly using Wi-Fi direct only, such UEs may communicate. The nature of the user may change, however. For example, the user may not try to communicate Wi-Fi direct to share an application. Instead the user may try to reach out to emergency services. When emergency services are not available, the user may try to establish communication with other victims to form a V2V network.
Some challenges may exist. For example, proximity services that were available using network assisted D2D are not valid any more, because the cell towers are not available. Moreover, conventionally V2V support is totally omitted when considering the disaster. For example, the system may be unable to retain the same cluster and to inform the UEs to use the same to establish V2V.
Furthermore, conventionally devices that are in proximity (for example UE1-4 may share profiles earlier among themselves but not with UE5) cannot help victim UE5 to be part of the group for V2V communication. Similarly, there is no conventional way for devices that are idle to wake up for V2V and to be part of some group.
If there is no guidance from the network, then conventionally each device may try to do ad hoc discovery and may quickly drain the battery. Such network formation may take a long time, and convergence of the network may not scale. Existing ad hoc protocols are not efficient for such purposes. For example, existing ad hoc protocols do not scale well, do not know the number of nearby nodes prior to the disaster, and do exhaustive scanning, which can drain the battery quickly.